The present invention relates in general to test equipment and, more particularly, to diagnostic, test and information systems.
Today, there are various hand held testers used in connection with the maintenance and repair of motor vehicles. Typically, these testers comprise cables attached to a microprocessor based device. The cables, for example, include a cable that connects to the motor vehicle battery and another cable that connects to an electrical system or component of the motor vehicle to measure voltage and current, as well as a data cable that connects to the engine control module to transmit information about operation of the vehicle to the hand held tester or to enable the tester to control various motor vehicle functions. See, for example, Tech 1, "Cartridges and Accessories," September, 1989.
Unfortunately, the cables connected to the motor vehicle are typically heavy and stiff. Consequently, the hand held tester is unweildly to operate, which is inconvenient to the user. Furthermore, the display screen on the hand held tester is small, and therefore, only a minimal amount of information can be displayed to the user.
Regarding the display of information to the user, the trend in the motor vehicle service bay is toward greater access to information relating to maintenance and repair. This trend requires the user to have a larger display screen incorporated into his or her test equipment and many connections to the motor vehicle, as well as to a dealership local area network (LAN).
Historically, motor vehicle manufacturers have provided printed information regarding maintenance and repair. As a service to motor vehicle maintenance and repair personnel, the manufacturers provided published information, such as manuals, for reference during maintenance and repair of motor vehicles. However, published information requires a large amount of storage space. More recently, motor vehicle manufacturers have provided maintenance and repair information on microfiche which is periodically updated. Although microfiche reduces storage requirements, microfiche can be misfiled and microfiche readers are cumbersome to use.
Today, various computer-based systems exist for providing motor vehicle maintenance and repair information. Some of these computer-based systems also comprise instruments to perform measurements in connection with motor vehicle evaluation and diagnosis. For example, one such computer-based system is the Model HP27070B ("TestBook"), available from Hewlett-Packard Company, Palo Alto, Calif. See, "HP TestBook," Hewlett-Packard Company Part No. 5091-9697E, September, 1993.
The TestBook system is a portable integrated personal computer and test system that provides compact mobile test and information tool for use in the motor vehicle service bay or on a road test. The TestBook system comprises a 486-microprocessor-based person computer, an integrated adjustable VGA liquid crystal display (LCD) panel and touchscreen interactive user interface having a capacitative touch-activated screen, and a built-in CD-ROM drive to provide faster and easier access to the latest service procedures and information for maintenance and repair of a motor vehicle. Built-in measure instrumentation and a programmable communications interface offer a test capability for computer-aided diagnostic applications. The TestBook system can be custom-configured to meet various MS-DOS, Windows, or OS/2 application requirements.
While the TestBook system provides ready access to a large amount of information needed for maintenance and repair of a motor vehicle, cables that connect to the vehicle must be attached to the measurement instrumentation integrated into the system. Consequently, as in the case of hand held testers, the TestBook system is unwieldy and is typically set on a work surface, such as a workbench or tool chest, during use. Therefore, the user does not have ready access to the integrated interactive display of the TestBook system while he or she is under the hood of the motor vehicle.
Additionally, a test and information tool for maintenance and repair of a motor vehicle which, has a selectively detachable, remotely operated interactive display unit that controls a portable integrated personal computer and test system is disclosed in co-pending U.S. patent application Series Code/Ser. No. 08/421,591, filed on Apr. 5, 1995 and assigned to the same assignee as the present application. This motor vehicle test and information tool provides greater user mobility than the TestBook system, because the display unit is not encumbered by being integrated with the personal computer having the additional weight of measurement instrumentation tethered by cables connected to electrical systems and components, as well as the engine control module, of the motor vehicle.
However, the measurement instrumentation is integrated with the personal computer, which requires a specially designed housing to accommodate both the personal computer and measurement instrumentation. The integrated personal computer and measurement instrumentation must also meet environmental and safety requirements relating to test equipment used in a motor vehicle service bay.
A modular wireless diagnostic, test and information system comprising a combined user interface and main control module and at least one remotely controlled instrumentation module connected by wireless communication is disclosed in co-pending U.S. patent application Series Code/Ser. No. 08/504,935, filed on Jul. 20, 1995 and assigned to the same assignee as the present application. The combined user interface with main control module has an interactive display which enables the user to command the functions of the remotely deployed instrumentation module(s) and enter data through interaction with the display, as well as execute application programs and displays information to the user. For example, one embodiment of the invention provides a combined user interface and main control module while having an interactive display, in which the user interacts with the display to access complex technical information employed to maintain and repair a motor vehicle and to control the instrumentation module(s) over a wireless communication link in the form of a radio-frequency (RF) local area network (LAN) to perform measurements on the vehicle, as well as to execute diagnostic routines and to display information to the user.
Although wireless system facilitate movement and positioning of the vehicle instrumentation modules and user interface, the wireless LAN circuitry and hardware components required to implement the wireless test diagnostic system are expensive. However, this increase in cost does not come with an increase in system performance. A disadvantage of wireless test diagnostic system is that the data being transferred from the instrumentation modules to the master control module has a slow data transfer rate. For example, typical data transfer rates for a wireless system would be 2 MB/sec. While this data transfer rate is sufficient for instrumentation channels having a slow data transfer rate, this data transfer rate may be insufficient for multiple vehicle instrumentation modules which have high speed data channels.
In addition, wireless communications systems are less reliable than traditional test diagnostic systems. Dependent on the system configuration, applications programs will often run on the server sending data to the user interface via the wireless LAN circuitry. This is problematic if the network goes down since failure of the network results in the wireless test diagnostic system being unable to communicate with the server. Further, because the applications programs are stored on the server, network failure would prevent the technician from operating the wireless test diagnostic system locally. In addition, wireless systems are more prone to failure due to their increased susceptibility to radio noise. Unfortunately, this problem is likely to increase due to the increased utilization of carrier frequency bands with wireless appliances such as cellular phone, etc.
An inexpensive, reliable, automobile test diagnostic system which can process information from high speed instrumentation data channels is needed.